Automatic tank switcher



Aug. 5, 1952 w; T. NANCE I 2,605,780

AUTOMATIC TANK SWITCHER Filed Dec. 13, 1949 4 Sheets-Sheet 1 DISCHARGELINE.

FIG. I

INPUT PIPE.

INVENTOR:

' WILLIAM 'T. NANCE HIS ATTORNEY Aug. 5, 1952 w. T. NAN-CE 2,605,780

AUTOMATIC TANK SWITCHER William T. Nance 5Q;

his A'i'i'or'neg A 5, 9 w. T. NANCE I 2,605,780

AUTOMATIC TANK SWITCHER Filed Dec. 13, 1949 4 Sheets-Sheet 3 mvfimok-FIG. 5 W\LL-IAM r. NANCE H\5 ATTORNE W. T. NANCE AUTOMATIC TANK SWITCHERAug. 5, 1952 4 Sheets-Sheet 4 Filed Dec. 15, 1949 SOLENOID TYPE FIG. IO

FIG. ll

\NVEJNTOR'.

H15 ATTORNEY Patented Aug. 5, 1952 AUTOMATIC TANK swrrornsn William T.Nance, Kilgore, Tex., assignor to Shell Development Company, SanFrancisco, Calif.,

I a corporation of Delaware Application December 13, 1949, Serial N 0.132,686

9 Claims. l

The present invention trol systems and pertains more particularly to anelectrically-operated automatic control system for selectivelycontrolling the flow of a fluid to any storage tank of a multiple-tankbattery.

In some industries, such as for example the petroleum industry, storagefacilities may comprise a battery of tanks. In order that a petroleumcrude or product may be received continuously from its source and at thesame time be measured and delivered by pipe line to other points, a tankbattery is employed consisting of at least two and generally four ormore large tanks all having valved inlet and outlet lines connected tocommon incoming and outgoing main pipe lines, respectively.

Many tank batteries are equipped with manually-operated valves in theinlet and outlet lines. Thus, when oil is delivered tothe tank battery:1 pumper or gauger manually opens the inlet valve to one tank, closesit when the tank is full or filled .to the desired level and repeatsthis operation with every empty tank while at the same time makingdeliveries from the full tanks. To eliminate the human element andmanpower neededto handle deliveries to and from a tank battery, variouscontrol systems have been devised for automatically routing saiddeliveries. Mechanical control devices havebeen found to be cumbersomeand generally adaptable for limited use only, whileelectrically-operated control systems employing relays, stepping relays,cam timers, etc., to perform automatic switching operations have beenexpensive and subject to operating failures.

It is, therefore, a primary object of this invention to provide aninexpensive electrically-operated tank switching control system ofsimple design adapted automatically to deliver fluid from a main pipeline or header to a battery of two or more storage tanks, said deliverybeing made only to an empty tank.

It is. also an object of the present invention .to provide anelectrically-operated tank switcher that automatically by-passes anytanks in a tank battery thatare either full or being emptied, or havebeen taken oif the line to be cleaned.

These and other objects and advantages of the present invention willbecome apparent from the following detailed description taken withreference to the drawing, wherein: I Figure l is an isometric viewillustrating a batteryof four storage tanks connected'to common deliveryand discharge pipe lines.

Figure 2 is a schematic diagram of the elecrelates to automaticcontrical circuit of an automatic tank switcher at the presentinvention.

Figures 3 and 4 are schematic diagrams of simplified electrical circuitsof the present tank switcher illustrating the position of the switchesduring various operations.

Figures 5 and 6 are schematic diagrams of other embodiments of thepresent tank switcher control system.

Figure 7 is a view in cross section of an electrically-operated inletvalve.

Figures 8 and 9 are front and top views of an embodiment of switch meanshaving two pairs of contacts and mounted adjacent a valve for actuationthereby.

Figure 10 is a view, partly in cross section, of a portion of a storagetank equipped with a floattype level indicator.

Figure 11 is an isometric view of switch means mounted adjacent anoutlet valve of the plug type.

Referring to Figure 1 of the drawing, a battery of four cylindricalstorage tanks I I, I2, I 3 and I4 is illustrated as being connectedthrough intake conduits I5, It, I! and I8 and headers l9 and 20 to anincoming pipe line 2|, as for example, from a separator (not shown).Flow through the inlet conduits I5, 16, I1 and I8 is controlled byelectrically-operated or relay-actuated inlet valves 22, 23, 24 and 25which may be actuated by suitable motor means, i. e., either of thesolenoid or motor-driven type, both types being well known to the art.The inlet valves are preferably of a type that will open when energizedand will automatically close in case of power failure. Since the valvesdo not comprise the novel part of this invention, they will not befurther described here except as diagrammatically shown in Figure 7 withregard to valve 22.

Each tank is also provided with a valved outlet line near or at thebottom for draining the tank. In Figure l, the discharge lines 26 and 21of tanks l3 and I 4 having valves 28.and 29 therein are connectedthrough header 30 to a main discharge pipe line 3|. It will beappreciated that tanks H and I2 are also provided with discharge linesthat are connected through header 34 with pipe line 3|. The dischargevalves may be manually, hydraulically or electrically operated, but willbe described for simplicity as manually-operated valves.

Each discharge valve, such as 28 or 29, is provided with electricalswitch means, such'as, forv example, a double-pole, single-throwmercurysealed type switch having one set of contacts normally open andthe other set normally closed. For example, as shown in Figures 8 and 9,a switch 38 is mounted on the outlet valve 29 so that one set ofcontacts 63 of the switch is closed when the valve is open while theother set of contacts 60 is closed when the valve is shut. For purposesof illustration, the switch 38 is shown as a bar member I pivotallymounted above outlet valve 29 on suitable support means IN. The two setsof contacts 30 and 69 of switch 38 may comprise a pair of switches, suchas, microswitches or switches of the sealed-mercury type. A collar I02mounted on the rising stem I03 of the valve tilts the bar I00 upwardwhen the valve is open, to open contacts 69 and close contacts 68.Similar switches 35, 3S and 31 are mounted on outlet valves of tanks II,I2 and I3 (Figure 2). In the event that the discharge valve on the tankis of the plug type rather than of the rising-stem type, the plug valveI29 (Figure 11) may have a shaft I30 attached to the plug within thevalve and movable therewith. The shaft I30 extends through the valvehousing and a bar member I3I is anixed to its extended end. Suitableswitch means may be mounted on said bar I3I, such as a double-polesingle throw sealed mercury type switch I32, having two sets of contactsI68 and IE9.

Mounted at any desired height on the wall of each tank and near the topthereof is an electrically operated liquid level indicator such as shownin Figure l at 39, 40, 4| or 42, that is, a level indicator havingelectrical switch means adapted to be closed or opened when the level ofliquid within the tank rises to a predetermined height. For example, thelevel indicator may be of the movable-float type having a singlepole,single-throw type switch mounted on or adjacent the float, said switchbeing closed by movement of the float when the rising liquid in the tankraises the float. The level indicator shown in Figure 10 comprises afloat I04 in a tank I05 secured to a movable arm I06 extending through afluid-tight flexible seal I0'I in the wall of the tank. A sealed-mercurytype switch I08 is mounted on the other end of arm I06 so that itscontacts are closed when the float is raised.

Electrical leads between the inlet valves 22, 23, 24, and 25, the liquidlevel indicators 39, 40, 4| and 42 and the switches 35, 36, 31 and. 36on the outlet valves in Figure 1 are mounted in conduits or singlecables 43, 44, 45 and 46 which lead through common conduits 41, 48 and49 to a control panel (not shown).

The electrical circuit of the present tank switcher system isschematically shown in Figure 2. The system comprises a plurality oftank circuits connected to a common power source 50 through a selectorswitch having a movable contact adapted to contact successively, aplurality of fixed contacts, the transfer from contact to contact beingeffected as a substantially instantaneous snap action. Instead of arotary snap-action type selector switch, a shorting type rotary switchmay be used. In this type of switch the rotating movable contact makescontact with the next position before breaking contact with the lastposition. The movement from one contact to another is substantiallyinstantaneous. For example, a singlepole selector switch having 2 to 16positions or more depending on the number of storage tanks in thebattery may be used. The switch 5| shown is a single-pole 4-positionswitch having four p0- sitions or stationary contacts 52, 53, 54 and 55.The movable contact 56' of the switch is fixedly connected to a shaft 51(diagrammatically represented by a broken line) driven by an electricalgear motor 58 or a motor whose speed has been reduced by a suitable geartrain. For example, a /60th H. P. gear motor, having an output shaftspeed of about 10 R. P, M., may be used. The rotary contact 56 of switch5| is connected to the power source 50 through leads 59 and 60 and amain switch 6 I.

In the following description and in the appended claims, the electricalcircuit interconnecting the inlet valve, float switch and outlet valveswitches on each tank with the motordriven rotary selector switch andthe power source will be spoken of as a tank circuit. Each tank circuit,for example, the tank circuit of storage tank II, comprises two branchcircuits in parallel havin rotary selector switch 5| in series with andcommon to both branch circuits. It is to be noted that the outlet valveswitch 35 has two sets of contacts 62 and 53. The other valve switches36, 31 and 38 also have similar pairs of contacts 64, and 65, 66 and 51,and 68 and 69, respectively.

For simplification in describing the parallel branch circuits, they areherein traced from the terminals 50. One branch circuit of the tankcircuit II comprises lead 60, switch 6|, lead 59, rotary arm 56 ofselector switch 5|, lead I5, solenoid valve 22, contacts 63 of switch 35and leads I6 and TI, all of said elements being arranged in series. Thiscircuit may be known as the inlet valve branch circuit. The other, ormotor, branch circuit comprises lead 60, switch 6|, lead 59, and arm 56of selector switch 5| which is in series with float switch 39, contacts62 of switch 35 and toggle switch I0, said switches 39, 35 and I0 alsobeing arranged in parallel with each other.

The individual tank circuits of the system may be provided withindicator lights 93, 94, and 96 which may be mounted on a. centralcontrol panel to glow whenever the inlet valve on any tank is energizedand hence open. The indicator lamps, being of high resistance, preventsany substantial amount of current from flowing directly from rotaryswitch 5| to lead TI.

Thus, with the main switch 6| and contacts 52 and 56 of the rotary snapswitch 5| closed, current will flow through leads I4 and "I5, throughthe coil of the solenoid valve 22, across closed contacts 63, which areclosed when the outlet valve is closed and through leads I6 and II tothe power supply 50. With current flowing through the inlet valvecircuit, the valve 22 opens and remains open until the tank issubstantially filled with liquid.

When the liquid level rises to the float switch or level indicator, itsswitch 39 is closed whereby the current by-passes valve 22, flowing fromlead I5 through lead 18, closed switch 39 and leads I9 and 80, to thegear motor 50, which is energized and rotates contact 56 of switch 5|from position 52 to 53. This breaks the circuit of motor 58 throughclosed switch 39 of tank II, and as the corresponding switch 40 of tankI2 is not yet closed, said tank I2 having not yet been filled, the motor58 is de-energized and stops rotating thereby leaving contacts 56 and 53closed or in register with each other. Current is now directed throughthe tank circuit of tank I2, said tank I2 being filled in a mannersimilar to that described for tank I I.

Preferably, the circuits of tanks H, 12,13 and I 4 are provided withby-pass switches 10, 11,12 and 13, respectively. These switches are usedto eliminate one or more tanks/from the switch ing sequence in the eventthat an empty tank is to be cleaned or repaired, or for. other'similarreasons. Thus, assuming that tank I12 was being cleaned and .its by-passswitch H had been closed as shown in Figure 3, after tank H has beenfilledas previously described andthe contact 5.6 of the rotary snapswitch has moved to contact "53, the 'current'will pass through. lead83, closed switch H and lead 80 tothe motor 58. The motor circuit oftank [2 is thus closed and the motor 58 remains energized "so as to 1'0-tate "the movable contact 56 to next position 54 as shown in Figure 4.

In Figure 4, float switch 39 is closed since tank vl I has been filledand by-pass switch "H is'closed to take tank l2 out of service.Contact-55 of rotary snap switch 51 has moved to position 54 so as toclose the tank circuit of tank l3 (Figure 2). Normally the coil of theinlet valve 24 would be energized, but since it is assumed that the tankI3 is being emptied, the outlet valve is open wherebycontacts 66 are.closed while contacts 61 have been opened. Thus, the current by-passesthe control winding or relay of inlet valve 24, flowing from rotaryswitch 51 through leads 85 and 86, closed switch 66 and leads 81, 88 and80, thus closing the motor branch circuit of tank i3 whereby the motor58 remains energized and contact '58 is moved to position 55. Withcontacts 55 and 56 of rotary switch 5| in register, the inlet valve"branch circuit of the fourth tank is closed, the current flowing fromswitch 5| through leads 8!! and 90, solenoid 25, lead 91, closed switch69 and leads 92 and 11 to the power source 50.

From the above description, itwill be seenthat the present tank selectoror switcher system will skip a tank in the battery that is full, beingemptied, or taken out of service for repairs or cleaning. Themotor-driven rotary selector switch continues to rotate until an emptytank is found having its outlet valve closed so that the contacts 63,'65, 6'! or 69 are closed, whereby the inlet valve branch circuit of theempty tank is closed thus energizing and opening anelectrically-operated inlet valve 22, .23, 24 or 25.

The incorporation in the motor branch circuit of the switches on theoutlet valves is for the purpose of preventing fluid from being runinadvertently into atank from which fluid isbeing discharged into theoutlet pipeline 3! (Figure 1). If desired, the switches 35, 36, Bland 38on the outlet valves, as shown in Figure may be dispensed with inanother embodiment of the present tank switcher system as showndiagrammatically in Figure 5. In this embodiment the four storage tanksare provided with electrically-controlled level indicators havingswitches 39, 40, 41 and 42 and tank circuits having by-pass switches 10,H, 12 and 7-3.

This embodiment, will operate in a manner similar to that of theembodiment shown in Figure 2 in delivering fluid selectively to emptytanks in the battery andshutting off the flow to each tank as it isfilled, -When a tank is emptied or cleaned its by-pass switch would beclosed so that the selector switch would skip that tank.

Another embodiment of the-present automatic switcher is shown in Figure6 wherein the bypass toggle switches 10, H, 12 and 73 of the circuit inFigure .2 have been eliminated. lhis sys 6. tem would operate .in amanner similar .to' that described with regard to Figure 2. When a tankis being cleaned its outlet valve may be left open so that the selectorswitch will skip that-tank. In the embodiment of Figure 6, the outletvalve switches I35, (I36, I31 and I38 are single-pole switches which areclosed-by the opening ofthe; corresponding outlet valves. Hence, uponthe opening of the outlet valve of thesecond tank, switch I36 is closed,the motor 58 remains energized and'the contact 15'6'moves to position 54thereby energizing the electric 'inlet 'valve 24 onthe empty third tank.

The circuitshownfin' Figure .2 may alsobe equipped'with a manualselector switch 9! which, through leads B0, 98, -99 and 89, connectsthemotor '58 directly to "the by-passing the tank circuits. The closing ofswitch 91 causes the motor-driven rotary snap switch 5! to rotatecontinuously. Thus, by open-' ing the manual selector switch 9! at'thecorrect moment, the rotary snap-switch 51 can be stopped in any of itspositions, 52, 53,54 or'55. This feature allows an operator to selectany tank in the battery as the starting point of'the filling cycle.

".I claim as my invention: 1. An automatic system for selectivelycontrolling'the'flow of fluid from a common source into a tank of amultiple-tank battery, eachof said tanks having-an intake line incommunication with said common source, electrically actuated inlet valvemeans in saidintake line, liquid level indicating means mounted on saidtank, said indicating means being equipped with electrioal switch means,and valved outlet means equipped with first and second electrical switchmeans, said system comprising a selector switch, prime mover means foractuating said selector switch, and a power source, said prime movermeans being electrically connected to eachfof said level indicatorswitch means, to one of said switch means on each of said tank outletvalve means and to said selector switch, saidtank in let valve means,said switch means on said level indicator and said outlet valve switchmeans of each of said tanks being connected in parallel through theselectorswitch to the power source.

2. A control system for selectivelyfillinga storage tank battery,comprising a plurality of tanks having electrically actuated fluid inletvalve means, liquid level indicating means on each tank responsive tothe rise of fluid to a predetermined level therein, first electricalswitch means actuated by said level indicating'm'eans, outlet valvemeans controlling the discharge of fluid from each tank, secondelectrical switch means having two pairs of contacts, one of said pairsof contacts opening as the other'closes, one of said pairs of contactsmounted adjacentsa'id outlet valve means for opening and closingtogether with said outlet valve means, a selector switch having amovable contact arm and a plurality of stationary contacts, an electricmotor for moving said contact arm, a power source, and tank controlcircuitmeans :for each tank in said battery for selectively energizingthe relay actuated valve and said selector switch motor, :said controlcircuit means being connected to the electric motor and to one of thestationary contacts of the selector switch, each of said tank controlcircuit means comprisingfirst and secand. parallel branch circuits inseries with a common contact of saidselector switch, said first branchcircuit comprising the level indicating power source thereby.

switch means and the first contact pair of said tank outlet valve switchmeans in parallel with each other and in series with the motor, wherebysaid motor is energized to rotate said selector switch on closure of anyof the first branch switch means, said second branch circuit comprisingsaid relay switch means of said inlet valve means in series with thesecond contact pair of said tank outlet valve switch means.

3. The control system of claim 2 including'bypass switch means inparallel with said level indicating switch means and said first contactpair of said tank outlet valve switch means, and in series with themotor, whereby said motor is energized to rotate said selector switch onclosure of one of said switch means.

4. A control system for selectively filling a tank battery, comprising aplurality of tanks having electrically actuated fluid inlet valve means,liquid level indicating means on each tank responsive to the rise offluid to a predetermined level therein, electrical switch means actuatedby said level indicating means, a selector switch having a movablecontact arm and a plurality of stationary contacts, an electric motorfor rotating said contact arm, a power source, and tank controlcircuit'means for each tank in said battery for selectively energizingone of said relay actuated valves and said selector switch motor, eachof said control circuit means being connected to the electric motor andto one of the stationary contacts of the selector switch, each of saidcontrol circuit means comprising first and second parallel branchcircuits in series with a common contact of said selector switch, saidfirst branch circuit comprising level indicating switch means in serieswith the motor, whereby said motor is energized to rotate said selectorswitch on closure of said switch means, said second branch circuitcomprising said relay switch means for operating said tank inlet valvemeans.

5. A control system for selectively filling a storage tank batterycomprising a plurality of tanks having solenoid-type inlet valves,liquid level indicating means on each tank responsive to the rise offiuid to a predetermined level therein, electrical switch means actuatedby said level indicating means, outlet valves controlling the dischargeof fiuid from each tank, switch means having two pairs of contactsmounted adjacent each outlet valve and actuated thereby, one of saidpairs of contacts opening as the other closes, one of said pairs ofcontacts opening and closing together with said outlet valve, a rotaryselector switch having a movable contact arm and a plurality ofstationary contacts, said rotary arm being adapted to close withsuccessive stationary contacts, an electric motor for rotatingsaidcontact arm, a power source, and control circuit means for each tankin said battery for selectively energizing one of said solenoid valvesand said selector switch motor, each of said control'circuit means beingconnected to the electric motor and to a different stationary contact ofselector switch, each of said control circuit means comprising first andsecond parallel branch circuits in series with a common contact of saidselector switch, said first branch circuit comprising the tank levelindicating switch means, the first contact pair of said outlet valveswitch means and by-pass switch means in parallel with each other and inseries with the motor, whereby said motor is energized to rotate saidselector switch on closure of any of said switch means, said secondbranch circuit comprising said sole- 8 noid valve in series with thesecond contact pair of said outlet valve switch means.

6. A system for automatically controlling the fiow of fluid from acommon source into a tank of a multiple-tank battery, each tank havingan intake line in communication with said common source, electricallyactuated inlet valve means in said intake line, liquid level indicatingmeans mounted on said tank, said indicating means being equipped withelectrical switch means, and valved outlet means equipped with first andsecond electrical switch means, said first switch means opening whensaid second switch means closes, said second switch means opening andclosing together with said outlet valve means and being connected inseries with said tank inlet valve means, said system comprising a rotarysnap-type selector switch, an electric motor for rotating said selectorswitch, and a power source, said selector switch motor beingelectrically connected to each of said level indicator switch means tosaid first outlet valve switch means and to said selector switch, saidselector switch motor being responsive to the closure of any of saidswitch means, said relay switch controlled inlet valve means, saidswitch means on said level indicator and said first outlet valve switchmeans of each of said tanks being connected in parallel through thecommon selector switch to the power source.

'7. A system for automatically controlling the flow of fluid from acommon source into a tank of a multiple-tank battery, each tank havingan intake line in communication with said common source, electricallyactuated inlet valve means in said intake line, liquid level indicatingmeans mounted on said tank, said indicating means being equipped withelectrical switch means, and valved outlet means equipped withelectrical switch means, said system comprising a selector switch, primemover means for actuating said selector switch, and a power source; saidprime mover means being electrically connected to each of said levelindicator switch means, to said tank outlet valve switch means and tosaid selector switch, and being responsive to the closure of any of saidswitch means to actuate said selector switch, said tank inlet valvemeans, said switch means on said level indicator and said tank outletvalve switch means of each of said tanks being connected in parallelthrough the common selector switch to the power source.

8. An automatic system for controlling the fiow of a liquid from acommon source to a plurality of tanks forming a battery, each of saidtanks having an inlet valve, an outlet valve, said system comprising asource of power, a selector switch having a plurality of fixed contactsand a movable contact adapted to close in succession with said fixedcontacts, said movable contact being electrically connected to saidsource of power, electromagnetic actuating means at every tank adaptedupon energization to open the inlet valve thereof, each of saidelectromagnetic actuating means being connected to one of said fixedcontacts, a motor electrically connected to said power source andmechanically connected to said movable contact, said motor being adaptedupon energization to actuate said movable contact into closure with thenext fixed contact, first means in circuit with said motor to energizesaid motor, said means comprising a level indicator switch at each tankadapted to be closed upon the liquid reaching the level of saidindicator, and second means in parallel with said first means toenergize said motor, said second means comprising a switch mounted atthe outlet valve of each tank, said switch being adapted to close whensaid valve opens.

9. An automatic system for controlling the flow of a liquid from acommon source to a plurality of tanks forming a battery, each of saidtanks having an inlet valve and an outlet valve, said system comprisingtwo power terminals, a selector switch having a plurality of fixedcontacts and a movable contact adapted to close in succession with saidfixed contacts, said movable contact being electrically connected to oneof said terminals, a plurality of tank control circuits each connectedon one side to one of said fixed contacts, each of said tank controlledcircuits comprising two parallel branches, the first branch comprisingin series electromagnetic actuating means adapted upon energization toactuate the tank inlet valve and a first switch actuated by the tankoutlet valve to close together therewith, the second branch comprisingin parallel a second switch adapted to be closed by the liquid rising ina tank to a predetermined level and a third switch actuated by the tankoutlet valve and adapted to close when said first switch opens, each ofsaid first branches being electrically connected on its other side tothe second power terminal, and an electric motor mechanically connectedto said movable contact and adapted upon energization to actuate saidmovable contact, each of said second branches being connected on itsother side to the second power terminal through said motor.

WILLIAM T. NANCE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,116,549 Zenner May 10, 19382,340,070 McCauley Jan. 25, 1944 2,340,576 Bacon Feb. 1, 1944 FOREIGNPATENTS Number Country Date 494,295 Great Britain of 1938

